The invention relates generally to material conveying systems, such as to pneumatic partial-vacuum transporting systems, more particularly to the collection and conveying of wastes, such as to the conveying of household wastes. Such systems are presented in publications WO 2009/080880, WO 2009/080881, WO 2009/080882, WO 2009/080883, WO 2009/080884, WO 2009/080885, WO 2009/080886, WO 2009/080887 and WO 2009/080888, among others. The invention also relates to waste feeding means, such as to input points or refuse chutes, with which waste is conveyed, typically by gravity, e.g. from higher input apertures in residential buildings to a lower collection space or corresponding container.
Systems wherein wastes are conveyed in piping by means of a pressure difference or suction are known in the art. In these, wastes are conveyed long distances in the piping by sucking. It is typical to these systems that a partial-vacuum apparatus is used to bring about a pressure difference, in which apparatus negative pressure is brought about in the material conveying pipe with partial-vacuum generators, such as with a fan, with vacuum pumps or with an ejector apparatus. A material conveying pipe typically comprises at least one valve means, by opening and closing which the replacement air coming into the material conveying pipe is regulated. Waste input points, e.g. rubbish containers or refuse chutes, are used in the systems at the waste material input end, into which waste input points material, such as waste material, is fed and from which waste input points the material to be conveyed is conveyed into a material conveying pipe by opening a discharge valve means, in which case, by means of the suction effect brought about by the aid of the partial vacuum acting in the material conveying pipe and also by the aid of the surrounding air pressure acting via the refuse chute, material such as e.g. waste material packed into bags, is conveyed from the refuse chute into the material conveying pipe and onwards to a reception point, where the material being transported is separated from the transporting air and conveyed for further processing or e.g. into a shipping container. The pneumatic waste-conveying systems in question can be utilized particularly well in densely populated urban areas. These types of areas have tall buildings, in which the feeding in of wastes into a pneumatic conveying system for wastes is performed via an input point, such as a refuse chute arranged, in the building.
Material can be conducted from an input point along a refuse chute into a container that is lower in the vertical direction, or an intermediate container can be in connection with the input points, into which intermediate container material fed from an input point is initially conducted and from where the waste material is conveyed onwards along the material conveying piping to a reception point.
The volume of the intermediate container that is between the input aperture of a waste input point and the discharge valve typically varies according to the embodiment. Typically the volume can be 100-600 l. An advantage of using an intermediate container is that it can increase the capacity of the input point, in which case the actual conveying system does not need to be started often. Depending on the application site, the conveying system is used 1-3 times a day to convey the material that has collected in the intermediate container. An advantage of a conventional intermediate container is also that the energy consumption of the conveying system can be reduced, because more waste can be conveyed with the same conveying cycle. One drawback, among others, of known solutions is that the space requirement of an intermediate container, especially when an input pipe is used as an intermediate container, is large. Typically an input pipe applied in a vertical attitude as an intermediate container becomes long, and a rather deep excavation pit must be arranged in the ground to install it. The excavation work is expensive, particularly in rocky areas where blasting is required for achieving the trench needed. The excavation work is expensive, particularly in rocky areas where blasting is required for achieving a trench. The installation depth of a typical intermediate container according to solutions known in the art is in the region of 2.5-3.5 m. The typical installation depth in the installation of the material conveying piping of a pneumatic wastes conveying system is smaller than this, in the region of 1-1.5 m.
A discharge valve, which opens and closes the connection from the intermediate container to the material conveying pipe, in many cases requires a separate space, i.e. a so-called pit, from where the discharge valve and its actuators can be serviced and installed.
A problem that arises in cases in which a separate discharge valve, i.e. waste valve, is not used is that the material can travel in an undesired manner into the material conveying pipe as a result of a pressure difference between an input point and the material conveying pipe and/or possible leakage air of an input point.
The aim of the present invention is to achieve a completely new type of solution in connection with the intermediate containers of the input points and material conveying pipings of a wastes conveying system, by means of which solution the drawbacks of known solutions are avoided. One aim of the invention is to achieve a solution by the aid of which an effective and operationally reliable solution can be achieved, wherein a discharge valve, i.e. waste valve, is not needed between the intermediate container of an input point and the material conveying piping. Another aim is to achieve a solution for compensating a change in volume resulting from a pressure difference of an intermediate container of pneumatic negative pressure systems for material, so that undesired displacement towards the material conveying pipe of the material fed into the intermediate container is avoided. Yet another aim is to achieve a solution for compensating leakage air of an intermediate container of an input point, so that undesired displacement into the material conveying pipe of the material fed into the intermediate container is avoided.